1. Field of the Invention
The present invention relates to a wireless communication system, and more particularly to a method for transmitting a reference signal which allows a base station of a wireless communication system to provide a location based service, and an apparatus for the method.
2. Discussion of the Related Art
Conventionally, a geographical location of a mobile station is calculated by measuring time delays of signals transmitted from a plurality of cells. Therefore, three or more signals are needed to measure the location of the mobile station. Even though a variety of methods for calculating the MS location using three or more signals are present, an observed time difference of arrival (OTDOA) technique has generally been used.
FIG. 1 is a conceptual diagram illustrating an OTDOA technique for measuring the MS location.
Referring to FIG. 1, the OTDOA technique has been used to measure the MS location using a difference in time points where signals transmitted from individual cells arrive at a mobile station. The MS measures time delays of signals received from individual cells, and reports the measured time delays to either a serving cell or an anchor cell. The serving cell measures the location of a corresponding MS using the reported time delays.
In this case, the signal transmitted from each cell to the MS is a Location Based Service-Reference Signal (LBS-RS), and the MS must identify the LBS-RS received from each cell. In addition, when establishing the LBS-RS transmitted from each cell to the MS, a reception power and time delay of the LBS-RS must be considered. In order to allow the MS to more effectively detect the LBS-RS received from each cell, a method for generating the LBS-RS sequence and a resource allocation method need to be considered.